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Evaluating the potential of early Pliocene mollusc shells from Peru as El Niño records
The interaction between the El Niño-Southern Oscillation (ENSO) and long-term future global warming is uncertain. Some models link past and future ¿hothouse¿ climates to a shallowing of the east Pacific thermocline and a shift towards a permanent ¿El Nino-like state¿ in the east Pacific. This is in contrast to other models indicating little change in the ENSO system under ¿hothouse¿ conditions. The early Pliocene, characterized by prolonged global warmth, provides a good testing ground for these conflictive theories. Since ENSO events are tightly coupled to the annual cycle it is essential to use paleoclimate-archives with seasonal resolution to resolve individual ENSO events. The stable oxygen isotopes of mollusc shells could provide the first proxy-record for ENSO events during the early Pliocene. We will evaluate the potential of different mollusc species, from several Pliocene exposures in coastal Peru, as climate archives. A range of analytical methods (scanning electron microscopy, X-ray diffraction, cathodoluminescence) will be applied to develop a screening procedure for diagenetic modifications. Diagenetically unaltered mollusc shells will be selected for stable isotope analysis of seasonal temperature variability.
Assessing the role of the Indian Ocean in global climate change: A paleoperspective
The proposed research project forms the basis for an innovative and multi-disciplinary approach aimed at a better understanding of the role of the Indian Ocean/Monsoon system in global climate change. The specific questions to be addressed are:
(1) Is the pronounced warming of the Indian Ocean since 1950 a result of anthropogenic warming, or is it within the range of natural, multi-decadal climate variability?
(2) How do sea surface temperature (SST) changes in the tropical Indian Ocean impact on rainfall over the surrounding continents?
The approach chosen is to develop long (up to 400 years), multi-core geochemical proxy records measured at coral and tree ring chronologies. The proxy records will be used to reconstruct interannual to centennial changes of SST and rainfall in two key areas of Indian Ocean climate variability: Indonesia and East Africa. A major outcome of the project will be the combination of coral and tree ring chronologies to document the impact of Indian Ocean SST changes on rainfall over teleconnected land areas.